Numerous devices have been proposed for groundwater sampling and monitoring, such as described in my U.S. Pat. Nos. 4,669,554 and 5,046,568. These devices are for short-term use but in some cases for geological or operational reasons it may be desirable to leave the device in the ground for reuse. In such cases, however, to reduce costs of such devices, and their use, it is desirable to be able to withdraw and reuse the drive rods after the device has been inserted into the ground without interfering with the usefulness of the device for its intended purpose. In addition, where a device is to be used for air injection, vacuum extraction or controlled sampling, it is desirable to provide a good annular seal between the device and the ground after the device is driven into the ground. It is also desirable to maintain such a seal while the drive rods are withdrawn after the drive point device has been placed in the ground.
The present invention provides a novel drive point device, means for retrofitting existing drive points, and other similar direct-push devices, such as the BAT ENVIRO PROBE sampling device, which permits reuse of the drive rods while also providing a seal between the device and the ground to facilitate air injection, vacuum extraction and groundwater sampling.